Posted
by
timothy
on Friday August 12, 2011 @06:33PM
from the fossil-ventriloquism dept.

thebchuckster writes "Scientists say they have found the first evidence that giant sea reptiles — which lived at the same time as dinosaurs — gave birth to live young rather than laying eggs. They say a 78 million-year-old fossil of a pregnant plesiosaur suggests they gave birth to single, large young."

But it's in a way upsetting to see so many dinosaur "established facts" I thought I knew turn out to be wrong. They were supposedly crawling out of the water to lay eggs like turtles! This is actually the second shock relating to plesiosaurs, they also were found recently to be warm blooded.

Being warm-blooded isn't that much of a surprise- we've known birds descended from warm-blooded dinosaurs for decades.

Yes, but plesiosaurs are not dinosaurs so it means yet another branch of reptiles were warm-blodded. There is also evidence that Pterosaurs were warm blooded. Given how far back these branches had a common ascestor, the question becomes: why are crocodiles not?

I was recently reading somewhere that crocodiles (and other Crocodilia) were at one time warm blooded. The evidence being that they have a 4 chamber heart like most warm blooded animals. It was theorized that they reverted to being cold blooded at some point in their evolution.Interestingly crocodilia also have a neo-cortex and diaphragm unlike all other extent reptiles.As usual Wikipedia has a bit about it, http://en.wikipedia.org/wiki/Crocodilia#Internal_organs [wikipedia.org]

there's a wonderful story in some sf anthology i read back in the dim ages. a scientist does an operation on some alligators to restore the 4chambered heart, and the alligators then grow wings, become dragons, and conquer the world.

thanks. i wasn't sure if endor and endore were the same person. endore wrote the screenplay for that peter lorre movie where he gets transplanted hands from a murderer. also wrote other horror-type screenplays.

But the evidence that all our favourite childhood dinosaurs were warm blooded is very recent, many in the last two years; sure there were theories in decades past but those were not the mainstream view. Cold, slow, sluggish....now they're hot, fast!

Well I don't find the idea of the plesiosaur being warm blooded or giving live birth upsetting. Now what's upsetting is that T-Rex might have been a scavenger. The proud king of the dinosaurs turns out to be a great big mooch who uses his size and strength for intimidation, like an unemployed guido roommate. Upsetting.

Does it make you feel better to know that the proud symbol of our nation, the bald eagle, does the same thing? They regularly steal kills from smaller raptors, and outright feed on carrion. It'd be odd if T-Rex didn't use his size to bully his way into free meals. Even primary scavengers hunt opportunistically, and T-Rex was well equipped to kill whatever it could catch.

That comparison is why I wasn't upset by the later (as known to me) revelation that T-Rex very

In the grand scheme of things, you are correct that the those who espouse the scientific method should be happy that their theories are proven wrong and human knowledge increased. However, we are still fickle humans and hate to see our work that we poured our heart and soul into get trashed in the name of progress. Many people cannot disassociate their ego from their work. I've known many programmers who do not like code reviews for that reason. No matter how much they want to acknowledge that it makes

That's probably a pretty common way of visualizing it, but the previous work isn't really getting trashed, is it? Were it not for the original work being publicized, there might not have been a competing idea at all, or at least not as soon. Challenges to canon are often still reliant on the existence of the canon in the first place. That's reason to be proud of scientific challenges to one's work, not upset by them. Maybe for science there should be a corollary to the old cliche, "imitation is the most

That's what it feels like, and that's why people initially have a strong emotional reaction to it. The various levels of the brain are all operating simultaneously -- the 'fight-or-flight' part and the higher-level cognitive part. We continue to have emotional, child-like reactions, but our higher-level cognitive functioning arrests and overrides such reactions.

But anybody that believes we truly know jack shit from THAT far back is just a fool IMHO. Hell there are still human languages we have NO clue how to read, buildings where we still haven't figured out how exactly they were able to get joints to fit that well using primitive tools, and those are things that are just centuries old, not a blip compared to this stuff.

I believe it was Plato who said something to the effect of "The wise man admits he knows nothing" and we have such a teeny tiny slice of fossils c

I'd mod this up, if I hadn't instigated this slice of the conversation. I cackle when I read about physicists confidently extrapolating from string theory or dark matter when those notions are anything but certain themselves. There are some days when even the Big Bang still smacks of religion to me, the way some experts treat it as a fait accompli. It worries me that these days, in archaeology, physics, astronomy, and astrophysics especially, we're stepping far over the fine line between what is truly ve

Perhaps it's a microcosm of the scientific world at large, but most of our dinosaur knowledge is based on "this is the first idea that popped into my head when I saw the thing, so we'll call it true until proven otherwise". The iguanadon, for example, was thought to have horns on its nose until a full skeleton was discovered and it was revealed that they were thumbs. Don't get me wrong, I don't care that we're creating imperfect theories based on limited knowledge which are expanded when more is discovered; that's how science works and how it should work. What I find to be particularly annoying is when these theories are taught as unchallenged fact. There was one species of dinosaur that was "discovered" in the form of a single bone, but sketches of the full animal were showing up in textbooks. If all you have is a single bone, at least put an asterisk beside the picture please! Maybe our knowledge would advance faster if we knew what exactly we knew and what we don't know.

1- Plesiosaurs are NOT dinosaurs.2- Most fully aquatic vertebrates descended from land animals are expected to be born in live birth. Eggs from non-amphibian land vertebrates (amniotes) are not suitable for underwater development, so the choices are to maintain land access for reproduction or live-birth. Many species of plesiosaurs seem to have been physiologically incapable of going on land and surviving (much like whales) so live birth was generally assumed... without proof yet. In this case as in the ca

Shouldn't be too surprising- livebearing shows up in all sorts of families that typically lay eggs- especially aquatic animals.
Everyone is familiar with the humble guppy. You buy one for your daughter despite your better judgement- one week later you're overrun with the gaudy ugly fish as the live young start popping out everywhere.
Many species of snail give birth to live young. Or "nearly so". Malaysian Trumpet snails and Quilted Melania two "cloning" species can pop out up to 9 live babies at a time. Even sexually reproducing snails can give live birth- species of Tylomelania from Sulawesi lay a single egg at a time that disolves before your eyes (if you're lucky) to reveal a minature snail.
That doesn't mean live-bearing fish or mollusks are common- and if this dino gave live-birth, it doesn't mean that it was common with dinosaurs either.

Very interesting. I suppose it makes logical sense that sea living creature would find it difficult to safeguard eggs, and with its size these would be very noticeable (and nutritious!). I guess it is similar to whale sharks nowadays, which are ovoviviparous in their reproduction (wikipedia link as below): the "embryos develop inside eggs that are retained within the mother's body until they are ready to hatch. Ovoviviparous animals are similar to viviparous species in that there is internal fertilization and the young are born live, but differ in that there is no placental connection and the unborn young are nourished by egg yolk; the mother's body does provide gas exchange (respiration), but that is largely necessary for oviparous animals as well."

Browsing further, the Science article seems to address this and indicates that they were fully viviparous (like us, I guess). Just reading the abstract now, unfortunately - though interested if anyone can chime in on the science?

Sometimes I run across news about discoveries where the commentators are all surprised, but in ways that make me think we need to get over ourselves:) as the utmost pinnacle of evolution or some such nonsense and just realise that we are no more than a combination of various biological strategies that had already been "invented" in numerous other branches of life. We're just a happy accident of much larger processes.

I find your comment very interesting, and frankly, a relief of sorts.I was starting to feel like I was alone with this POV.That made me question it, and still could find no 'chink in the armor', which caused me to question others about it.That was a circuitous path that led back to no 'chink in the armor'.

However, the comment about single young is even more interesting - as whale sharks are even bearing very many (live) young. Maybe different again? (no expert here, just curious!)

I'm no expert either. Generally the smaller the litter, the less the mortality rate. In this case it possibly would point to the parent[s] looking after the young unlike sharks where the young are left to fend for themselves.

You're correct with regards to sharks, but so far all evidence suggests dinosaurs laid eggs (including modern ones as birds). The creature being discussed in this article is a large marine reptile from the time of the dinosaurs, but it isn't a dinosaur. There are many extinct and large reptilians besides dinosaurs, including plesiosaurs [wikipedia.org], mosasaurs [wikipedia.org], ichthyosaurs [wikipedia.org] (who also had live birth), and pterosaurs [wikipedia.org] (known to lay eggs), etc.

The line keeps getting blurred between dinosaurs, reptiles, birds and mammals. It's hard to justify a warm blooded reptile since cold bloodedness is a large part of being a reptile. Live birth is nothing new. A number of snake species give birth live. A lot of ancient animals that are called reptiles probably weren't. Pterosaurs are still called flying reptiles inspite of the fact that every condition that gave them the title of reptile has been disproven. It's mostly dogma that keeps them reptiles. Ancien

What about the idea that there were multiple lines of fish who started walking on land pushing the division of some of the groups back even further so the last common ancestor of Mammals, Birds, Reptiles, and Amphibians was a fish in the Devonian period?

Maybe instead of a common tetra pod ancestor there was a line of walking fish who had live birth and those were the ones who gave rise to mammals. While another line gave rise to reptiles and birds, while a similar branch gave rise to amphibians?

By making comparisons with modern animals, such as whales, which give birth to larger, single young and then go on to care for them, Dr O'Keefe and his colleague, Luis Chiappe from the museum, attempt to infer something about plesiosaur behaviour.

... plesiosaurs, the authors suggest, might have been doting parents.

But Dr Smith was less convinced. He said that it was "certainly quite possible... but is very speculative".

Of course it's speculative, but it's still plausible. I would expect any animal who gives birth to one young at a time to spend time with its offspring until the offspring is strong enough to survive on its own.

The more we learn, the more it seems to me that different epochs of life on Earth were in many ways much more familiar than we used to believe. If only we could see into the past...

A little off topic...

When you get right down to it, behaviour doesn't fossilise

True, mostly. But sometimes we get very lucky... Velociraptor vs. Protoceratops [bhigr.com]. This gave some insight to how velociraptors used their big claws. (For gripping and stabbing, not slashing.)

> But sometimes we get very lucky... Velociraptor vs. Protoceratops [bhigr.com].//

That looks incredibly fake to me. I just can't imagine the conditions in which these animals would die in mid fight like that and remain perfectly preserved. From the fossil it appears both animals died at exactly the same time and were preserved without being fed on by scavengers big enough to carry off a single bone.

I have guppies in my aquarium, they give birth to live babies (they don't lay eggs). And theoretically dinosaurs are more evolved/advanced than mere fish, so it shouldn't be a surprise at all that some of them are livebearers.